ISLAMABAD — The extremist Pakistani Taliban has formally confirmed the death of its chief in last week’s American drone strike in eastern Afghanistan and announced the appointment of his successor.

The slain militant leader, Mullah Fazlullah, and his four key commanders were traveling in a vehicle in the Afghan border province of Kunar on June 13 when missiles fired from an unmanned aircraft, or drone, hit them just before midnight.

In a statement issued Saturday, the militant Tehreek-e-Taliban Pakistan (TTP), commonly referred to as the Pakistani Taliban, said that its leadership council has named Mufti Noor Wali Mehsood as the group’s new chief and Mufti Mazahim as his deputy.

The militant outfit praised slain Fazlullah’s services for TTP saying he had become a “headache for slaves of America in Pakistan and Afghanistan.”

Two days after the U.S. confirmed conducting the drone strike, Afghan President Ashraf Ghani informed leaders in neighboring Pakistan that their most wanted man had been eliminated.

The Pakistani foreign ministry this past Thursday also gave its own confirmation of the death of militant leader, describing it as a “significant development in fighting terrorism.”

Islamabad maintains that TTP leaders have taken refuge in “ungoverned spaces” in border areas of Afghanistan and are orchestrating terrorist attacks against Pakistan from those sanctuaries.

Pakistan blames TTP for killing tens of thousands of people, including security forces, in suicide and targeted terrorist attacks during the past decade in Pakistan.

The U.S. State Department had offered a $5 million reward for Fazlullah, accusing him of directing numerous high-profile attacks against American and Pakistani targets since he was appointed the group’s leader in 2013.

U.S. and Pakistani officials say Fazlullah also was behind a December 2014 attack on the Army Public School in Peshawar in which 151 people were killed, including more than 130 children.

New TTP chief

Fazlullah’s two predecessors also were eliminated by American drones in the Pakistani border region of Waziristan, the TTP’s birthplace.

The group’s new chief Wali also is known as Abu Mansoor Asim. All TTP factions and leaders swore allegiance to Wali, noted Saturday’s militant statement.

Wali’s appointment has returned the group’s leadership to the Mehsud-led Taliban faction, which is credited for founding TTPa decade ago to fight and keep Pakistani security forces from militant bases near the Afghan border.The Mehsud tribe is mostly based in Pakistan’s South and North Waziristan border regions.

Fazlullah was a non-Mehsud and belonged to mainland Pakistan’s Swat region.The slain leader’s elevation to the top position had upset leaders of the Mehsud Taliban and prompted some to break their alliance with TTP.

Analysts say that under its new leadership, TTP’s splinter factions could try to reunite and threaten counterterrorism gains Pakistan has made in the Waziristan region over the past decade. Military officials say the region has been cleared of all terrorist infrastructure and reconstruction work is currently underway.

Wali is a religious scholar and author.Until his elevation as TTP’s chief, he also was heading the group’s publication department. Wali has fought alongside the Afghan Taliban when the Islamist group was ruling and fighting to bring all of Afghanistan under its control in late 1990s

After a U.S.-led military coalition ousted the Taliban from power in 2001 for harboring the al-Qaida terrorist network, Wali fought alongside the Taliban insurgency against foreign forces.

Gunfight in Waziristan

Saturday’s announcement by the militant group came just hours after Pakistani officials said security forces raided a suspected TTP hideout hide out in a South Waziristan village.

An exchange of gunfire left two soldiers and six “terrorists” dead, an army statement said. It added that security forces recovered weapons, ammunition along with communication equipment “through which terrorists were in communication with their handlers across the border in Afghanistan’s Paktia province.

For its part, the TTP claimed the clash erupted after its fighters attacked Pakistani forces.